Assembly and System of Datacommunication Cables and Connectors

ABSTRACT

A datacommunication interconnection system includes (a) an extension trunk cable-connector assembly and (b) a trunk cable-connector assembly. The extension trunk cable-connector assembly comprises: a first cable including a plurality of first subunits, each of the first subunits comprising a plurality of twisted pairs of conductors; a jack attached to one end of the cable; and a plug attached to an opposite end of the cable. Each of the jack and the plug includes a contact for each of the conductors of the cable. The trunk cable-connector assembly comprises: a second cable including a plurality of second subunits, each of the second subunits comprising a plurality of twisted pairs of conductors; a plug attached to one end of the second cable and connected with the jack of the extension trunk cable; and a plurality of RJ-45 connectors attached to subunits at an opposite end of the second cable.

RELATED APPLICATIONS

This application is a continuation claiming priority from U.S. patentapplication Ser. No. 13/312,095, filed Dec. 6, 2011, which applicationis a continuation claiming priority from U.S. patent application Ser.No. 12/763,410, filed Apr. 20, 2010, now U.S. Pat. No. 8,075,348, whichclaims priority from U.S. Provisional Patent Application No. 61/171,899,filed Apr. 23, 2009, and from U.S. Provisional Patent Application No.61/241,456, filed Sep. 11, 2009, the disclosure of each of which arehereby incorporated herein in their entirety.

FIELD OF THE INVENTION

The present invention relates generally to datacommunication components,and more particularly to datacommunication cables and connectors.

BACKGROUND

A network patching system is typically used to interconnect the variouscommunication lines within a closet, computer room or data center. In aconventional network patching system, the communication lines areterminated within a closet or cabinet in an organized manner via one ormore patch panels mounted on a rack or frame. Multiple ports areincluded in the patch panel, typically in some type of organized array.Each of the different ports is connected with a communications line. Insmall patching systems, all communications lines may terminate on thepatch panels of the same rack or cabinet. In larger patching systems,multiple racks or cabinets may be used, wherein different communicationslines terminate on different racks or cabinets. Interconnections betweenthe various communications lines are made by connecting patch cords tothe ports. By selectively connecting the various communications lineswith patch cords, any combination of communications lines can beinterconnected.

A patch panel typically includes connectors (such as RJ-45 jacks) on itsfront surface that receive mating connectors (such as RJ-45 plugs) forinterconnection with other equipment. In most patch panels, a cable witha plurality of individual conductors is routed to the rear of the patchpanel. The connection between the cable and the connectors of the patchpanel is typically made through punch-down connectors or insulationdisplacement contacts (IDCs). Making these connections can be rathertime-consuming, as can making changes to the connections subsequently.Moreover, as performance requirements become more stringent, it may bedifficult for some types of connections to meet higher (e.g., Category6A) performance requirements.

In view of the foregoing, it may be desirable to provide otherconfigurations for patch panels and the like that simplifiesinterconnections and/or enhances performance.

SUMMARY

As a first aspect, embodiments of the present invention are directed toa cable-connector assembly. The assembly comprises: a trunk cablecomprising a plurality of subunits, each of the subunits comprising aplurality of twisted pairs of conductors and a shield circumferentiallysurrounding the plurality of twisted pairs; and a connector attached toeach end of the cable, each of the connectors including a contact foreach of the conductors of the cable. Such an assembly can be utilized toquickly and easily connect datacommunication components, even those thatrequire enhanced (e.g., Category 6A) performance.

As a second aspect, embodiments of the present invention are directed toan extension trunk cable-connector assembly. This assembly comprises: acable including a plurality of subunits, each of the subunits comprisinga plurality of twisted pairs of conductors; a jack attached to one endof the cable; and a plug attached to an opposite end of the cable. Eachof the jack and the plug includes a contact for each of the conductorsof the cable. Such an extension trunk cable can be used to span othercabling used to interconnect enhanced performance datacommunicationcomponents.

As a third aspect, embodiments of the present invention are directed toa datacommunication interconnection system comprising (a) an extensiontrunk cable-connector assembly and (b) a trunk cable-connector assembly.The extension trunk cable-connector assembly comprises: a first cableincluding a plurality of first subunits, each of the first subunitscomprising a plurality of twisted pairs of conductors; a jack attachedto one end of the cable; and a plug attached to an opposite end of thecable. Each of the jack and the plug includes a contact for each of theconductors of the cable. The trunk cable-connector assembly comprises: asecond cable including a plurality of second subunits, each of thesecond subunits comprising a plurality of twisted pairs of conductors; aplug attached to one end of the second cable and connected with the jackof the extension trunk cable; and a plurality of RJ-45 connectorsattached to respective ones of the second subunits at an opposite end ofthe second cable.

As a fourth aspect, embodiments of the present invention are directed toa datacommunication connector unit, comprising: a housing; a printedwiring board mounted within the housing; a plurality of RJ-45 jacksmounted on the printed wiring board and accessible from one side of thehousing; and a backplane connector mounted to the printed wiring boardand electrically connected to the RJ-45 jacks, the backplane connectorbeing accessible from a second side of the housing.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a schematic perspective view of a cable-connector assemblyaccording to embodiments of the present invention.

FIG. 2 is a schematic perspective view of the connector unit of theassembly of FIG. 1 with the upper portion of the housing removed forclarity.

FIG. 3 is a perspective section view of the cable of the assembly ofFIG. 1.

FIG. 4 is a perspective view of a connector unit of FIG. 1 mounted tothe end of the cable of FIG. 3.

FIG. 5 is an exploded end view of a mating jack and plug of theconnector unit of the assembly of FIG. 1.

FIG. 6A is an exploded side view of the mating jack, plug and backplanearray of the connector unit of FIG. 2.

FIG. 6B is a side view of one of the cards of the jack of FIG. 6A.

FIG. 6C is an exploded side view of another embodiment of a mating jackand plug according to embodiments of the invention.

FIG. 6D is an exploded top view of the mating jack and plug of FIG. 6C.

FIG. 7 is an exploded perspective view of a cable-connector assemblyaccording to additional embodiments of the present invention.

FIG. 8A is a section view of a shielded twisted pair cable of theassembly of FIG. 7.

FIG. 8B is a section view of an unshielded twisted pair cable of theassembly of FIG. 7.

FIG. 9A is a section view of a twisted pair cable according toembodiments of the present invention, wherein the subunits of the cableare unfolded relative to each other.

FIG. 9B is a section view of the twisted pair cable of FIG. 9A, whereinthe subunits are in a folded condition.

FIG. 9C is a perspective section view of the twisted pair cable of FIG.9B showing the subunits in a folded condition and covered by a jacket.

FIG. 10 is a perspective view of the housing and RJ-45 jacks of theassembly of FIG. 7.

FIG. 11 is a perspective view of six assemblies of FIG. 7 mounted in apatch panel.

FIG. 12 is a schematic diagram illustrating an interconnection schemefor a data center that utilizes the assembly of FIG. 1.

FIG. 13 is a schematic diagram illustrating a cross-connection schemefor a data center that utilizes the assembly of FIG. 1.

FIG. 14 is a schematic diagram illustrating an interconnection andcross-connection scheme for a core switch that utilizes the assembly ofFIG. 1, wherein two different architecture arrangements are shown.

FIG. 15 is a schematic diagram illustrating another interconnectionscheme for a core switch that utilizes the assembly of FIG. 1.

FIG. 16 is a schematic diagram illustrating a cross-connection schemefor an access switch that utilizes the assembly of FIG. 1.

FIG. 17 is a schematic diagram illustrating an interconnection andcross-connection scheme for an access switch that utilizes the assemblyof FIG. 1.

FIG. 18 is a schematic diagram illustrating a cascading cross-connectionscheme utilizing multiple cable assemblies of FIG. 4 with a connector ofFIG. 6 on the opposite end of the cable.

DETAILED DESCRIPTION

The present invention will be described more particularly hereinafterwith reference to the accompanying drawings. The invention is notintended to be limited to the illustrated embodiments; rather, theseembodiments are intended to fully and completely disclose the inventionto those skilled in this art. In the drawings, like numbers refer tolike elements throughout. Thicknesses and dimensions of some componentsmay be exaggerated for clarity.

Unless otherwise defined, all terms (including technical and scientificterms) used herein have the same meaning as commonly understood by oneof ordinary skill in the art to which this invention belongs. It will befurther understood that terms, such as those defined in commonly useddictionaries, should be interpreted as having a meaning that isconsistent with their meaning in the context of the relevant art andwill not be interpreted in an idealized or overly formal sense unlessexpressly so defined herein.

In addition, spatially relative terms, such as “under”, “below”,“lower”, “over”, “upper” and the like, may be used herein for ease ofdescription to describe one element or feature's relationship to anotherelement(s) or feature(s) as illustrated in the figures. It will beunderstood that the spatially relative terms are intended to encompassdifferent orientations of the device in use or operation in addition tothe orientation depicted in the figures. For example, if the device inthe figures is turned over, elements described as “under” or “beneath”other elements or features would then be oriented “over” or “above” theother elements or features. Thus, the exemplary term “under” canencompass both an orientation of over and under. The device may beotherwise oriented (rotated 90 degrees or at other orientations) and thespatially relative descriptors used herein interpreted accordingly. Asused herein, “vertical” has the conventional meaning, i.e., upright; orat a right angle to the horizon.

The terminology used herein is for the purpose of describing particularembodiments only and is not intended to be limiting of the invention. Asused herein, the singular forms “a”, “an” and “the” are intended toinclude the plural forms as well, unless the context clearly indicatesotherwise. It will be further understood that the terms “comprises”and/or “comprising,” when used in this specification, specify thepresence of stated features, integers, steps, operations, elements,and/or components, but do not preclude the presence or addition of oneor more other features, integers, steps, operations, elements,components, and/or groups thereof. As used herein the expression“and/or” includes any and all combinations of one or more of theassociated listed items.

Where used, the terms “attached”, “connected”, “interconnected”,“contacting”, “mounted” and the like can mean either direct or indirectattachment or contact between elements, unless stated otherwise.

Also, as used herein the term “connector” is intended to encompasstelecommunications connectors and devices employed to facilitate theinterconnection of telecommunications cords and cables for thetransmission of signals therebetween. A connector may include atermination device at the end of a cord or cable, an adapter thatfacilitates the interconnection of two termination devices, a jack,plug, or the like typically employed with copper cables and cords, orother devices that provide a location or site for the interconnection ofcables and cords.

Referring now to the drawings, a cable-connector assembly, designatedbroadly at 10, is shown in FIG. 1. The assembly 10 includes a cable 22and a connector unit 23 at each end thereof. These components arediscussed in greater detail below.

Referring now to FIG. 3, the cable 22 comprises six separate cablesubunits 24, each of which includes 4 twisted pairs of conductors 25.The conductors 25 are conventional twisted pair conductors and need notbe described in detail herein. Each of the subunits 24 iscircumferentially enclosed in a conductive shield 26 to reduce crosstalkbetween cable subunits 24. The set of six subunits 24 is thencircumferentially enclosed in a jacket 28, which is typically formed ofa polymeric material.

The conductors 25 of the cable 22 are attached at each end to arespective 24-pair plug 34 (FIGS. 1, 4 and 5). Each plug 34 includes aplurality of apertures 34 a for receiving contacts from a respectivemating 24-pair jack 38 (FIGS. 1, 5 and 6A). In some embodiments (knownas “breakout” cables), the plug 34 may be replaced with six RJ-45 plugs.In other embodiments, the conductors 25 may be connected directly totelecommunications equipment via a punch-down connector or the like.

Each connector unit 23 includes a backplane jack 38 as described above.As can be seen in FIGS. 5 and 6A, each backplane jack 38 includesprojecting contacts 39 that extend into and mate with contacts withinthe apertures 34 a of the plugs 34. The contacts 39 of the jacks 38 areconnected in rows with respective cards 44 (see FIGS. 6A and 6B). Thecards 44 are arranged in a stacked relationship and are covered with aplastic housing 42. Each of the cards 44 includes traces 45 that carrysignals to and from the contacts 39.

Referring to FIGS. 6C and 6D, an alternative backplane jack 138 and plug134 are illustrated therein. The jack 138 and plug 134 are of a 2×9arrangement. An exemplary backplane jack is the FX-Z connector,available from Foxconn Technology Group (Tucheng City, Taipei, Taiwan).

Each backplane jack 38 is mounted within a housing 48 (FIG. 2). SixRJ-45 jacks 46 are integrated on a printed wiring board 49 and mountedin a wall of the housing 48 opposite the jack 38. The printed wiringboard 49 is mounted in the housing 48 between the cards 44 and the jacks46 with traces that carry signals therebetween. The RJ-45 jacks 46 maybe Category 6A jacks which typically include integrated crosstalkcompensation components/structure/circuitry that enable the jacks toachieve Category 6A performance standards (as defined byTIA-568-B.2-10). Exemplary jacks 46 are described in U.S. Pat. Nos.7,204,722 and 7,264,516, which are incorporated herein by reference, andare available under model numbers MGS-500 and MGS-600 from CommScope,Inc. (Hickory, N.C.). The RJ-45 jacks 46 can provide interconnectionlocations to other telecommunications equipment via RJ-45 plugs, such asthose designated at 47 in FIG. 2.

It is contemplated that, in some embodiments, an assembly 10 asdescribed above may be able to deliver Category 6A electricalperformance, particularly with respect to return loss, and internal andalien crosstalk performance. In particular, the connector units 23 canprovide Category 6A performance, as can the cable 22.

Another embodiment of a cable-connector assembly, designated broadly at110, is shown in FIGS. 7-11. The cable-connector assembly 110 includes acable 122 that has four cable subunits 124, each of which includes fourtwisted pairs of conductors 125. The subunits 124 may each becircumferentially surrounded by a shield 126 as shown in FIG. 8A, or maylack a shield as in FIG. 8B. The shielded embodiment of FIG. 8A includesa surrounding jacket 128; the unshielded embodiment of FIG. 8B isarranged as a quartet with the jackets of individual subunits 124attached via glue, looming or the like (this arrangement may be employedfor foiled twisted pair subunits also). Another alternative cablearrangement is illustrated in FIGS. 9A-9C and designated broadly at122′. The cable 122′ includes four subunits 124′ (each of which containsfour twisted pairs of conductors 125′) that are connected by webs 127′that are generally coplanar and offset from the center of each subunit124′ when the cable 122′ is in an unfolded condition as in FIG. 9A. Asshown in FIG. 9B, the subunits 124′ can be folded into a foldedcondition in which they form a quartet much like the subunits of thecables of FIGS. 8A and 8B. The quartet is then covered with a jacket128′. Those skilled in this art will appreciate that other numbersand/or arrangements of subunits may be employed in cables according toembodiments of the present invention.

The assembly 110 includes connector units 123 on each end. As seen inFIG. 7 the connector unit 123 includes the male 2-pair×9 connector 134of FIGS. 6C and 6D (available from Foxconn Technology Group, TuchengCity, Taipei, Taiwan) that attaches to the individual conductors 125 ofthe cable 123. The connector 134 mates with the mating female 2-pair×9connector 138 of FIGS. 6C and 6D (also available from Foxconn) that isattached to a housing 148. In the wall opposite the connector 138, thehousing 148 includes four Category 6A RJ-45 jacks 146; these areconnected with the connector 138 via a backplane similar to that shownin connection with the assembly 10 (see FIG. 10). Those skilled in thisart will appreciate that the male and female connectors may be switchedin some embodiments.

As can be seen in FIG. 11, multiple assemblies 110 may be attached to abezel 150 to form a patch panel 152 having, in the illustratedembodiment, a total of 24 RJ-45 jacks 146 for interconnection with patchcords. In some embodiments, the assembly 110 may have only one housing148, or in other embodiments the assembly 110 may terminate with theconnector 134. Also, in some embodiments the assembly 110 may take theform of a breakout cable that has RJ-45 jacks on one end.

In still further embodiments, the assembly may take the form of anextension trunk cable in which one end terminates with a connector(jack) 134 and the other end terminates with a connector (plug) 138.Such cable assemblies can enable the cables of other systems andassemblies of the present invention to be effectively lengthened (suchas is seen in FIG. 18).

FIGS. 12-18 illustrate different interconnection arrangements in whichthe assemblies 10, 110 and similar devices may be effectively utilized.Turning first to FIG. 12, the interconnection of a data center 50 isshown. Connection of a core switch 51 with a server 52 can be achievedvia an assembly 10 connected with patch cords 54, 56. A similarinterconnection scheme is shown in FIG. 13, in which a core switch 61 isconnected with a server 62. In this scheme, an assembly 10 is connectedwith the server 62 via patch cords 64 (one of which is shown in FIG.13). The assembly 10 is then connected via patch cords 66 with anotherassembly 10′ that lacks one connector unit 23; instead, on that end thecable 22 is broken out into its individual cable subunits 24, each ofwhich is attached via a Category 6A RJ-45 plug 68 to the core switch 61to form a data center 60.

Turning now to FIG. 14, a data center 70 that serves differentarchitecture schemes is shown. A core switch 71 is connected via trunkcables 72 a, 72 b to aggregation switches 73 a, 73 b. The trunk cables72 a, 72 b may be configured as the cable 22 above with a 24-pair plug34 on each end. The aggregation switch 73 a is connected to a server 74a with an assembly 10 via standard RJ-45 patch cords 76, 78. Thisarrangement is suitable for Middle of Rack (MoR) and End of Rack (EoR)architectures. The aggregation switch 73 b is connected to a server 74 bvia an assembly 10′ that is connected with an assembly 10 via patchcords 75; the assembly 10 is then connected to the server 74 b via patchcords 77. This arrangement is suitable for modular, scalable data centertopologies and architectures and is also known as a cross-connectionscheme.

Turning now to FIG. 15, a data center 80 exhibits two different Top ofRack (ToR) architecture schemes. A core switch 81 is connected via trunkcables 82 a, 82 b (of the configuration described above for cables 72 a,72 b) to two ToR switches 83 a, 83 b. The ToR switch 83 a is connectedto a plurality of servers 84 a via patch cords 85. The ToR switch 83 bis connected to a plurality of servers 84 b via an assembly 10 (whichmay connect to the switch 83 b via a plug 34, RJ-45 plugs, or punch-downcontacts) and patch cords 87.

Referring now to FIG. 16, a horizontal cross-connect system 90 is showntherein. An access switch 91 is connected to an assembly 10′, which inturn is connected to a patch panel 92 with patch cords 97. The patchpanel 92 is then connected via patch cords 93 to jacks 94, which arethen connected to workstations 95 with patch cords 96. FIG. 17 shows asimilar arrangement 90′, but includes an assembly 10 between theassembly 10′ and a consolidation point 97. The consolidation point 97 isthen connected to the jacks 94 with patch cords 93.

FIG. 18 illustrates an assembly 200 in which multiple assemblies 110,110′ can be interconnected in a concatenated fashion via interveningextension trunk cables of the construction of the cables 23, 123. A coreswitch 202 is connected to a breakout cable 204 of the same constructionas the cables 123 with the exception that on one end the terminatingconnector is replaced with RJ-45 plugs 204 a attached to each of thecable subunits. The breakout cable 204 is connected to two extensiontrunk cables 206, 208. The construction of the extension trunk cables206, 208 are identical: they have a plug 134 and a jack 138 on oppositeends of the cable 122. The extension trunk cable 208 is connected to ahousing 148 at the opposite end through a jack 138. Thus, the length ofan assembly 110 is effectively increased through the use of theextension trunk cables 206, 208. The RJ-45 jacks of the housing 148 areconnected to the RJ-45 jacks of another assembly 110′ via patch cords210. The assembly 110′ has two extension trunk cables 212, 123″. Theextension trunk cable 123″ connects with housing 148″ through a jack138. The use of extension trunk cables 212, 123″ effectively lengthensthe assembly 110′. The RJ-45 jacks of the housing 148″ are thenconnected to the RJ-45 jacks of a server 62 via patch cords 214.

In some embodiments, the trunk cables 123′ are supplied in differentlengths (such as multiples of 10 meters), and the breakout and extensiontrunk cables 204, 206, 212, 123″ are supplied in prime number meterlengths, such that virtually any typical desired length of cable can becreated by inserting a combination of extension trunk cables at the endof the main trunk cable 123′ or the breakout cable 204. As such, twopieces of equipment can be easily and rapidly interconnected with acable assembly of a desired length. Of course, the cables may besupplied in non-prime number lengths as well in other embodiments.

Those skilled in this art will recognize that, through the use ofassemblies of the types described above, technicians can interconnectequipment in a “plug-and-play” fashion, and can do so with cables thathave on either end (a) a housing with RJ-45 jacks mounted therein, (b)RJ-45 jacks “broken out” from the cable, or (c) a suitable connector(jack or plug) that can mate with a mating connector of anothermulti-subunit cable, which can provide the technician with theflexibility to interconnect equipment in almost any desired manner.Also, the “plug-and-play” arrangement should ensure the technician thatthe desired level of performance (e.g., Category 6A) is achievable withthese components.

In some embodiments, it may be desirable to include “intelligentinfrastructure system” features to the assemblies 10, 110 to enable thetracking of connections between different pieces of equipment. Anintelligent infrastructure system can be implemented in a number ofways, including out-of-band communication, a dedicated control channel,RFID, Serial ID, mechanical sensors or other unique identification inthe terminations and ports, and other known methods of tracking patchingconnections. In additional embodiments, intelligent tracking may beperformed for each subunit of the above-described cables.

Moreover, the trunk and extension cables of the present invention may beemployed in a system in which the cables and their jacks/plugsthemselves plug directly into panels and equipment (e.g., core switches,servers and the like), rather than requiring RJ-45 connectors forinterconnection. Such an arrangement can produce a system with muchhigher performance. For example, if the prior-described systems were“10G” systems when using a 16-pair cable, use of such panels andequipment may produce a “40G” system with a 16-pair cable.

The foregoing embodiments are illustrative of the present invention, andare not to be construed as limiting thereof. Although exemplaryembodiments of this invention have been described, those skilled in theart will readily appreciate that many modifications are possible in theexemplary embodiments without materially departing from the novelteachings and advantages of this invention. Accordingly, all suchmodifications are intended to be included within the scope of thisinvention as defined in the claims. The invention is defined by thefollowing claims, with equivalents of the claims to be included therein.

That which is claimed is:
 1. A cable-connector assembly, comprising: atrunk cable comprising a plurality of subunits, each of the subunitscomprising a plurality of twisted pairs of conductors and each twistedpair of conductors having a shield circumferentially surrounding thetwisted pair of conductors; and a connector attached to each end of thecable, each of the connectors including contacts for conductors of thecable.
 2. The cable-connector assembly defined in claim 1, wherein theplurality of subunits comprises either 4 or 6 subunits.
 3. The assemblydefined in claim 2, wherein the plurality of subunits equal 4 subunits.4. The cable-connector assembly defined in claim 3, wherein the 4subunits are surrounded by a cable jacket formed of a polymericmaterial.
 5. The cable-connector assembly defined in claim 1, whereinthe subunits are separated from each other within the trunk cable. 6.The cable-connector assembly defined in claim 5, wherein each subunit issurrounded by a subunit jacket.
 7. The cable-connector assembly definedin claim 5, wherein each subunit has 4 twisted pairs of conductors. 8.The cable-connector assembly defined in claim 1, wherein said cableconnector assembly is capable of delivering Category 6A performance. 9.The cable-connector assembly defined in claim 1, wherein one of saidconnectors is a male connector and is attached to each of the conductorsof the cable.
 10. An extension trunk cable-connector assemblycomprising: a cable including a plurality of subunits, each of thesubunits comprising a plurality of twisted pairs of conductors; a jackattached to one end of the cable; and a plug attached to an opposite endof the cable; a plurality of shielding layers, each shielding layercircumferentially surrounding a respective one of the plurality oftwisted pairs of conductors, wherein each of the jack and the plugincludes contacts for conductors of the cable.
 11. The assembly definedin claim 10, further comprising features that enable connectivity and/orintegrity of the subunits to be tracked.
 12. The assembly defined inclaim 10, wherein the plurality of subunits comprises either 4 or 6subunits.
 13. The assembly defined in claim 12, wherein the plurality ofsubunits equal 4 subunits.
 14. The cable-connector assembly defined inclaim 13, wherein the 4 subunits are surrounded by a cable jacket formedof a polymeric material.
 15. The cable-connector assembly defined inclaim 10, wherein the subunits are separated from each other within thetrunk cable.
 16. The cable-connector assembly defined in claim 15,wherein each subunit is surrounded by a subunit jacket.
 17. Thecable-connector assembly defined in claim 15, wherein each subunit has 4twisted pairs of conductors.
 18. The cable-connector assembly defined inclaim 10, wherein said cable connector assembly is capable of deliveringCategory 6A performance.
 19. The cable-connector assembly defined inclaim 10, wherein one of said connectors is a male connector and isattached to each of the conductors of the cable.